Enma, the powerful sword introduced in the Wano Country arc of One Piece, did not directly replace any particular sword in Roronoa Zoro's arsenal. Instead, Zoro added Enma to his collection of swords alongside his existing blades.

Zoro's original three swords, which he wielded prior to obtaining Enma, are:

1. Wado Ichimonji: A sword with a white hilt and a circular guard. It was given to Zoro by Kuina, his childhood friend and rival.
2. Sandai Kitetsu: A cursed sword with a red hilt and a circular guard. Zoro acquired this sword while browsing a sword shop.
3. Shusui: A black-bladed sword with a white hilt. Zoro obtained Shusui after the events of the Thriller Bark arc.

With the addition of Enma, Zoro now wields four swords, making it a part of his current arsenal without directly replacing any of his previous blades.